The use of hand mirrors for examining inside the mouth during dental procedures is well known. Traditionally, most mirrors were utilized to examine the interior of the mouth and the exterior surfaces of the teeth. As such, they were large enough to provide the dentist or oral surgeon with an image which could be viewed with the naked eye. Endodontic procedures, however, involve work on the interior of a tooth within very small spaces and thus have produced the need for a substantially smaller mirror surface for providing an image of the interior dental tissue or root of the tooth.
During endodontic surgical procedures, such as retrofilling preparations on the inner end or tip of a tooth root, a small opening or aperture is formed, generally through the jaw bone and the tissue surrounding a tooth, to provide exposure of the dental root. To form the apertures for working on the tooth root, very small drills are utilized so that the required interior work space will be very small. The surgical work is performed using a surgical microscope to view the tooth root in the small work space that is created by drilling through the jaw proximate the tooth root. An endodontic mirror is used to provide a reflected optical image, and the microscope then magnifies the reflected optical image provided by the endodontic mirror for viewing by the surgeon. Because of the small work space, the endodontic mirror must be very small, but still must be capable of providing a bright, distortion-free optical image for magnification by the microscope.
Endodontic mirrors are available for such applications, as evidenced by U.S. Pat. No. 5,269,683, issued to Hickok et al. While the Hickok et al. mirror is suitable for providing a useful optical image, it has a variety of drawbacks which affect the quality of the optical image provided and thus affect the overall endodontic procedure. First, the mirror is a single surface mirror which has an exposed reflective surface of polished tungsten-carbide. The tungsten-carbide has been found to absorb a significant amount of visible light, thus reflecting an optical image of reduced brightness to the microscope. Endodontic surgical microscopes, however, require a large amount of light for work in the small, dark spaces of the interior of the jaw proximate a tooth root. Low light conditions and a darkened optical image during an endodontic microsurgical procedure are not only annoying to the surgeon, but also may affect the surgeon's ability to perform the procedure efficiently and properly.
An additional drawback to available endodontic mirrors is their susceptibility to damage by other endodontic instruments used during a microsurgical procedure inside the mouth. The mirrors are usually what are referred to as "first surface mirrors," and their reflective surface is exposed. Therefore, the reflective surface is easily scratched by irrigator tips and probes which are generally made out of stainless steel. Therefore, great care must be taken during the endodontic procedure to avoid contacting the exposed reflective surface with other, harder instruments. However, contact is often unavoidable and damage results. A damaged reflective mirror surface further degrades the optical image provided to the microscope.
One way to reduce such damage to the reflective surface is to provide a protective surface or layer on top of the reflective surface to thus create what is referred to as a "second surface" mirror. However, second surface mirrors have traditionally been subject to double imaging or "ghost" imaging. Light reflects from not only the second reflective surface, but also from the first protective surface, and thus provides second or ghost images of the area of interest. Ghost images are very undesirable in microscopic endodontic surgery wherein it is oftentimes difficult to obtain a suitable single optical image. The microscope magnifies these double images and makes detailed examination of the root end difficult.
Another drawback to existing endodontic mirrors is that they are susceptible to chemical and heat damage. Endodontic implements must be sterilized between uses. Usually a high temperature autoclave (.about.200.degree. C.) is used to heat the implements for sterilization. The reflective surface of first surface mirrors may be subject to warpage and other temperature-induced damage during autoclaving. Furthermore, aggressive chemicals utilized in chemical sterilization procedures degrade the optical surface. Still further, weak acids often present in the mouth can adversely affect an endodontic mirror's reflectivity.
Available endodontic mirrors have also been relatively expensive and generally are not made for use with universal dental handles. Each mirror is machined with its own dedicated handle which creates a substantial expense for the endodontic surgeon, who will generally require a number of endodontic mirrors having different sizes and shapes.
Accordingly, it is an object of the present invention to provide a highly reflective endodontic mirror which provides a bright optical image for microscopic surgical procedures.
It is another objective of the present invention to provide a mirror which is durable and damage resistant, and which may be manipulated with other surgical instruments in an endodontic procedure without degrading the reflective surface.
It is still another objective of the present invention to provide a clear, usable optical image without double imaging or ghost imaging.
It is another objective to provide an endodontic mirror which is relatively inexpensive and suitable for use with existing dental equipment such as universal dental handles.
It is still another objective of the present invention to provide an endodontic mirror which is highly resistant to repeated sterilization and exposure to chemical solutions which are encountered during endodontic procedures.